/* XTS: as defined in IEEE1619/D16 *	http://grouper.ieee.org/groups/1619/email/pdf00086.pdf *	(sector sizes which are not a multiple of 16 bytes are, *	however currently unsupported) * * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org> * * Based om ecb.c * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at your option) * any later version. */#include <crypto/algapi.h>#include <linux/err.h>#include <linux/init.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/scatterlist.h>#include <linux/slab.h> #include <crypto/xts.h>#include <crypto/b128ops.h>#include <crypto/gf128mul.h> struct priv {	struct crypto_cipher *child;	struct crypto_cipher *tweak;}; static int setkey(struct crypto_tfm *parent, const u8 *key,		  unsigned int keylen){	struct priv *ctx = crypto_tfm_ctx(parent);	struct crypto_cipher *child = ctx->tweak;	u32 *flags = &parent->crt_flags;	int err; 	/* key consists of keys of equal size concatenated, therefore	 * the length must be even */	if (keylen % 2) {		/* tell the user why there was an error */		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;		return -EINVAL;	} 	/* we need two cipher instances: one to compute the initial 'tweak'	 * by encrypting the IV (usually the 'plain' iv) and the other	 * one to encrypt and decrypt the data */ 	/* tweak cipher, uses Key2 i.e. the second half of *key */	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &				       CRYPTO_TFM_REQ_MASK);	err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);	if (err)		return err; 	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &				     CRYPTO_TFM_RES_MASK); 	child = ctx->child; 	/* data cipher, uses Key1 i.e. the first half of *key */	crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);	crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &				       CRYPTO_TFM_REQ_MASK);	err = crypto_cipher_setkey(child, key, keylen/2);	if (err)		return err; 	crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &				     CRYPTO_TFM_RES_MASK); 	return 0;} struct sinfo {	be128 *t;	struct crypto_tfm *tfm;	void (*fn)(struct crypto_tfm *, u8 *, const u8 *);}; static inline void xts_round(struct sinfo *s, void *dst, const void *src){	be128_xor(dst, s->t, src);		/* PP <- T xor P */	s->fn(s->tfm, dst, dst);		/* CC <- E(Key1,PP) */	be128_xor(dst, dst, s->t);		/* C <- T xor CC */} static int crypt(struct blkcipher_desc *d,		 struct blkcipher_walk *w, struct priv *ctx,		 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),		 void (*fn)(struct crypto_tfm *, u8 *, const u8 *)){	int err;	unsigned int avail;	const int bs = XTS_BLOCK_SIZE;	struct sinfo s = {		.tfm = crypto_cipher_tfm(ctx->child),		.fn = fn	};	u8 *wsrc;	u8 *wdst; 	err = blkcipher_walk_virt(d, w);	if (!w->nbytes)		return err; 	s.t = (be128 *)w->iv;	avail = w->nbytes; 	wsrc = w->src.virt.addr;	wdst = w->dst.virt.addr; 	/* calculate first value of T */	tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv); 	goto first; 	for (;;) {		do {			gf128mul_x_ble(s.t, s.t); first:			xts_round(&s, wdst, wsrc); 			wsrc += bs;			wdst += bs;		} while ((avail -= bs) >= bs); 		err = blkcipher_walk_done(d, w, avail);		if (!w->nbytes)			break; 		avail = w->nbytes; 		wsrc = w->src.virt.addr;		wdst = w->dst.virt.addr;	} 	return err;} static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,		   struct scatterlist *src, unsigned int nbytes){	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);	struct blkcipher_walk w; 	blkcipher_walk_init(&w, dst, src, nbytes);	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,		     crypto_cipher_alg(ctx->child)->cia_encrypt);} static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,		   struct scatterlist *src, unsigned int nbytes){	struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);	struct blkcipher_walk w; 	blkcipher_walk_init(&w, dst, src, nbytes);	return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,		     crypto_cipher_alg(ctx->child)->cia_decrypt);} int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,	      struct scatterlist *ssrc, unsigned int nbytes,	      struct xts_crypt_req *req){	const unsigned int bsize = XTS_BLOCK_SIZE;	const unsigned int max_blks = req->tbuflen / bsize;	struct blkcipher_walk walk;	unsigned int nblocks;	be128 *src, *dst, *t;	be128 *t_buf = req->tbuf;	int err, i; 	BUG_ON(max_blks < 1); 	blkcipher_walk_init(&walk, sdst, ssrc, nbytes); 	err = blkcipher_walk_virt(desc, &walk);	nbytes = walk.nbytes;	if (!nbytes)		return err; 	nblocks = min(nbytes / bsize, max_blks);	src = (be128 *)walk.src.virt.addr;	dst = (be128 *)walk.dst.virt.addr; 	/* calculate first value of T */	req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv); 	i = 0;	goto first; 	for (;;) {		do {			for (i = 0; i < nblocks; i++) {				gf128mul_x_ble(&t_buf[i], t);first:				t = &t_buf[i]; 				/* PP <- T xor P */				be128_xor(dst + i, t, src + i);			} 			/* CC <- E(Key2,PP) */			req->crypt_fn(req->crypt_ctx, (u8 *)dst,				      nblocks * bsize); 			/* C <- T xor CC */			for (i = 0; i < nblocks; i++)				be128_xor(dst + i, dst + i, &t_buf[i]); 			src += nblocks;			dst += nblocks;			nbytes -= nblocks * bsize;			nblocks = min(nbytes / bsize, max_blks);		} while (nblocks > 0); 		*(be128 *)walk.iv = *t; 		err = blkcipher_walk_done(desc, &walk, nbytes);		nbytes = walk.nbytes;		if (!nbytes)			break; 		nblocks = min(nbytes / bsize, max_blks);		src = (be128 *)walk.src.virt.addr;		dst = (be128 *)walk.dst.virt.addr;	} 	return err;}EXPORT_SYMBOL_GPL(xts_crypt); static int init_tfm(struct crypto_tfm *tfm){	struct crypto_cipher *cipher;	struct crypto_instance *inst = (void *)tfm->__crt_alg;	struct crypto_spawn *spawn = crypto_instance_ctx(inst);	struct priv *ctx = crypto_tfm_ctx(tfm);	u32 *flags = &tfm->crt_flags; 	cipher = crypto_spawn_cipher(spawn);	if (IS_ERR(cipher))		return PTR_ERR(cipher); 	if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;		crypto_free_cipher(cipher);		return -EINVAL;	} 	ctx->child = cipher; 	cipher = crypto_spawn_cipher(spawn);	if (IS_ERR(cipher)) {		crypto_free_cipher(ctx->child);		return PTR_ERR(cipher);	} 	/* this check isn't really needed, leave it here just in case */	if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {		crypto_free_cipher(cipher);		crypto_free_cipher(ctx->child);		*flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;		return -EINVAL;	} 	ctx->tweak = cipher; 	return 0;} static void exit_tfm(struct crypto_tfm *tfm){	struct priv *ctx = crypto_tfm_ctx(tfm);	crypto_free_cipher(ctx->child);	crypto_free_cipher(ctx->tweak);} static struct crypto_instance *alloc(struct rtattr **tb){	struct crypto_instance *inst;	struct crypto_alg *alg;	int err; 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);	if (err)		return ERR_PTR(err); 	alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,				  CRYPTO_ALG_TYPE_MASK);	if (IS_ERR(alg))		return ERR_CAST(alg); 	inst = crypto_alloc_instance("xts", alg);	if (IS_ERR(inst))		goto out_put_alg; 	inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;	inst->alg.cra_priority = alg->cra_priority;	inst->alg.cra_blocksize = alg->cra_blocksize; 	if (alg->cra_alignmask < 7)		inst->alg.cra_alignmask = 7;	else		inst->alg.cra_alignmask = alg->cra_alignmask; 	inst->alg.cra_type = &crypto_blkcipher_type; 	inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;	inst->alg.cra_blkcipher.min_keysize =		2 * alg->cra_cipher.cia_min_keysize;	inst->alg.cra_blkcipher.max_keysize =		2 * alg->cra_cipher.cia_max_keysize; 	inst->alg.cra_ctxsize = sizeof(struct priv); 	inst->alg.cra_init = init_tfm;	inst->alg.cra_exit = exit_tfm; 	inst->alg.cra_blkcipher.setkey = setkey;	inst->alg.cra_blkcipher.encrypt = encrypt;	inst->alg.cra_blkcipher.decrypt = decrypt; out_put_alg:	crypto_mod_put(alg);	return inst;} static void free(struct crypto_instance *inst){	crypto_drop_spawn(crypto_instance_ctx(inst));	kfree(inst);} static struct crypto_template crypto_tmpl = {	.name = "xts",	.alloc = alloc,	.free = free,	.module = THIS_MODULE,}; static int __init crypto_module_init(void){	return crypto_register_template(&crypto_tmpl);} static void __exit crypto_module_exit(void){	crypto_unregister_template(&crypto_tmpl);} module_init(crypto_module_init);module_exit(crypto_module_exit); MODULE_LICENSE("GPL");MODULE_DESCRIPTION("XTS block cipher mode");